This is Steven Salzberg's blog on genomics, pseudoscience, medical breakthroughs, higher education, and other topics, including skepticism about unscientific medical practices. Here's where I can say what I really think about abuses and distortions of science, wherever I see them.

Legalized pot is already saving $165 million per year in medical costs

A new study in the journal Health Affairs looked in great detail at prescription drug usage in U.S. states that have legalized medical marijuana. Researchers Ashley Bradford and David Bradford collected Medicare data for the period 2010-2013 to answer two questions: are patients choosing marijuana instead of prescription drugs for conditions that marijuana might treat, and what has been the overall effect on Medicare spending?

The bottom line: in 2013 alone, when 17 states had legalized medical marijuana, Medicare saved over $165 million. A simple extrapolation suggests that if all states legalize marijuana, annual savings could be triple that amount, $500 million. (Obviously this extrapolation is over-simplified: it depends on the actual populations of those 17 states, and it only considers Medicare. Commercial healthcare plans may save far more.)

The authors, a father-daughter team at the University of Georgia, looked at over 87 million prescriptions from the Medicare Part D database, focusing only on conditions where marijuana "might serve as an alternative treatment." These fall into nine specific categories for which at least some evidence suggests marijuana could help: anxiety, depression, glaucoma, nausea, pain, psychosis, seizures, sleep disorders and spasticity. The best clinical evidence of marijuana's benefits, according to the study, is for pain, for which the clinical evidence is "moderate"; most of the other conditions have evidence rated as low or very low.

Prescriptions fell for 8 out of 9 categories, with the biggest drop occurring for pain medication: in states with medical marijuana laws, physicians gave out 3645 fewer pain prescriptions per doctor, a difference that is highly statistically significant. Or, in raw numbers, the annual number of daily doses (in 2010-2013) per doctor in states without medical marijuana laws was 31,810. In states with medical marijuana, the number dropped to 28,165. That's an 11.5% drop. Depression and seizures both showed very significant reductions in prescriptions as well.

Prescriptions rose for only one condition: glaucoma. This too was expected–as the article explains,

"Clinical evidence is very strong that while marijuana sharply reduces intraocular pressure, the effect lasts only about an hour. As a result, new patients who seek glaucoma treatment after learning about the potential benefits of marijuana are likely to receive a prescription for an FDA-approved drug."

In an interview posted on the University of Georgia website, study co-author David Bradford states that they also wanted to know if medical marijuana laws were just a backdoor way to allow recreational marijuana use, or if people were really using it as medicine. He continues:

"What our evidence is suggesting is that ... there is a significant amount of actual clinical use at work here."

As of today, 24 states have medical marijuana laws on the books. This new study suggests that legalizing marijuana in all states would save hundreds of millions of dollars in Medicare costs, and even more money for people not covered by Medicare–not to mention the savings from no longer wasting law enforcement resources prosecuting marijuana use.

Opponents of legalization have argued since the 1930's that marijuana is a "gateway drug" that will lead to more serious drug abuse and that it increases criminal behavior, without (as Bradford and Bradford point out) any good evidence proving these links. This new study now provides a strong financial argument for legalization: legalizing marijuana, at least for medical use, will yield substantial savings for our health care system.